1. Field of the Invention
The present invention relates to a system for detecting a position of an underwater vehicle capable of moving three-dimensionally.
2. Description of the Related Art
A nuclear in-reactor inspection system that uses, for example, a three-dimensionally movable underwater inspection unit (underwater vehicle) to inspect structures formed inside a nuclear reactor is traditionally known (refer to JP-A-2005-315709, for example). The nuclear in-reactor inspection system described in JP-A-2005-315709 includes an underwater inspection unit that has detection means to detect state quantities relating to a position and attitude of the inspection unit, and a thruster for assigning a thrust to the inspection unit. The nuclear in-reactor inspection system also includes a control unit connected to the underwater inspection unit via a cable in order to control the position and attitude of the underwater inspection unit. The detection means of the underwater inspection unit is constituted by an acceleration sensor for detecting tri-axial (X-axial, Y-axial, and Z-axial) acceleration levels, a gyroscope for detecting tri-axial angular velocities, and a camera by which an object to be inspected is imaged with an emitted slit laser beam projected on the object. The control unit uses detection results of the detection means to compute any variations in a position of the underwater inspection unit, totalize the variations in the position of the underwater inspection unit, and thus compute an absolute position thereof.